1. Field of the Invention
The present invention relates to a foaming die device adapted to effect foaming in a headrest trim cover assembly (or a surface covering element for headrest) in an integral manner to form a headrest for use with an automotive seat, and also relates to a foaming process for forming the headrest, which entails forming a foam padding in the headrest trim cover assembly in an integral manner, using the foaming die device.
2. Description of Prior Art
For example, Japanese Laid-Open Publication No. 2012-245081 (JP 2012-245081 A) discloses a typical conventional process for forming a headrest for use with an ordinary automotive seat, which includes the step of installing a substantially U-shaped headrest stay in a trim cover assembly preformed in a bag-like three-dimensional shape, prior to the step of placing the trim cover assembly in a foaming die device. As usually found in the art, such substantially U-shaped headrest stay includes a pair of substantially-rectilinear stay portions (hereinafter, it shall be referred to as “first substantially-rectilinear stay portion” and “second substantially-rectilinear stay portion”) formed integrally therewith, which are adapted to be mounted in a seat back. On the other hand, the trim cover assembly is formed with a pair of stay passage holes (hereinafter, it shall be referred to as “first stay passage hole” and “second passage hole”) adapted for allowing the first and second substantially-rectilinear stay portions to be inserted therein and passed therethrough, respectively.
According to the conventional process, at first, a worker inserts the first substantially-rectilinear stay portion of the headrest stay into the second stay passage hole of the trim cover assembly, wherein the second stay passage hole is a hole in which the second substantially-rectilinear stay portion normally exists when the headrest stay is installed in the trim cover assembly. Then, the worker manages to continue on pushing that first substantially-rectilinear stay portion, via the second stay passage hole, into the inside of the trim cover assembly and causing the same to advance within the trim cover assembly towards the first stay passage hole, so that the first substantially-rectilinear stay portion eventually projects outwardly from the trim cover assembly through that first stay passage hole, while ascertaining that the second substantially-rectilinear stay portion passes through and yet remains in the earlier-stated second stay passage hole. In that way, the headrest stay is installed within the trim cover assembly, such that both first and second substantially-rectilinear stay portions pass through the first and second stay passage holes, respectively, and project outwardly from the trim cover assembly. Next, a foaming die device is provided, which has upper and lower dies. The trim cover assembly with the headrest stay thus installed therein is placed in and between two cavity regions respectively of the upper and lower dies, and then, the upper and lower dies are closed and mated with each other. Thereafter, a liquid foaming agent is injected via an injection nozzle into the inside of the trim cover assembly placed in those upper and lower dies and cured to form a foam padding filled in that trim cover assembly in an integral manner, so that a resulting headrest for automotive seat is produced.
However, in the above-described conventional headrest production process, at the step of pushing the first and second substantially-rectilinear stay portions outwardly through the first and second stay passage holes, respectively, prior to the trim cover assembly being placed in the dies, there has been a problem in that, when the first and second substantially-rectilinear stay portions are inserted in and passed through the respective first and second stay passage holes, a peripheral edge portion of each of the first and second stay passage holes, by the reason of its being in frictional contact about the corresponding substantially-rectilinear stay portion, is forcibly stretched outwardly from the outer surface of trim cover assembly. As a result thereof, a cylindrically projected local area is created in the peripheral end of each of the first and second stay passage holes and laid on and about the corresponding substantially-rectilinear stay portion outside of the trim cover assembly. Such cylindrically projected local area is therefore exposed exteriorly of the trim cover assembly, which undesirably impairs an outer aesthetic appearance of a resulting headrest. To avoid creation of the cylindrically projected local area, before placing the trim cover assembly in the dies, it is required or customary in the past for a worker to use a cylindrical stick for the purpose of pressing and turning over such cylindrically projected local area into the inside of the trim cover assembly. That is, the worker causes each of the first and second substantially-rectilinear stay portions to insert in a through-bore of such cylindrical stick and moves the cylindrical stick along the substantially-rectilinear stay portion towards the trim cover assembly, to the extent that the circular distal end of that cylindrical stick contacts and presses the afore-said cylindrically projected local area. Then, the worker continues to move the cylindrical stick further, so that a whole of the cylindrically projected local area is turned over reversely relative to the stay passage hole and positioned inside of the trim cover assembly, thereby avoiding external exposure of that cylindrically projected local area. In that way, the outer peripheral region of each of the first and second stay insertion holes is made flat and even on the outer surface of the trim cover assembly, hence maintaining the outer aesthetic appearance of resulting headrest. This is an ordinary conventional means to avoid external exposure of the afore-said projected area in question, which is created about each of the first and second stay passage holes. However, such conventional method has imposed annoying inefficient steps upon the workers, because he or she is compelled to use the cylindrical sticks for each of many trim cover assemblies, troublesomely, prior to the step of placing the trim cover assembly in the foaming die device.